1. Field of the Invention
The field of the invention relates to installing a series of uniformly sized and spaced depressions, or SNAP's, in the surface of an asphalt road. The installation uses a cutting head and a cam member, the cam member having a plurality of camming groups, to form the desired series. Such installation being performed without requiring pausing the machine during installation. Means to milling through each cut or making plunge cuts, or near plunge cuts, is provided. Additionally, the optional placement of skip patterns within the series of depressions is provided.
2. Description of the Prior Art
Sonic noise alert pattern, (SNAP), are a series of depressions formed in the surface of asphalt. The pattern has the purpose of providing vibration, and therefore noise, when the tires of a vehicle traverse them longitudinally. Road departments use these depressions as a safety device. Longitudinally adjacent the edge of a highway or along the center line which divides the opposing directional traffic flows are common locations of placement. They act to alert a driver that his or her vehicle has extended beyond the normal driving surface. Beyond this normal driving surface many dangerous conditions exist for a vehicle traveling near the posted speed limit. These dangers include dirt or gravel shoulders, guardrail barriers, signs, mailboxes, intersecting roadways or driveways and disabled vehicles.
The various specifications for the placement and physical dimensions of the individual depressions can vary from state to state and even within a particular state. A common size and placement, used only for illustration and not limitation, places the individual depressions twelve inches apart from center of one depression to center of the adjacent depressions. The measurements of the individual depressions being seven inches from back trailing edge to front leading edge with a depth, at the deepest point, of one half inch and a lateral length across of sixteen inches. These specifications result in five inches of uncut surface between each set of adjacent depressions. Therefore, the above specifications would require fifty-two hundred and eighty cuts per mile.
A recent innovation in the specifications for the installation of SNAP depressions requires a skip pattern be incorporated within the series. One example of such a series has eight depressions spaced as detailed above followed by an uncut area equal to the normal placement of four depressions. Such installation affords reasonable coverage of a highway while reducing the expense of installation. Limited access highways and rural roads are likely locations for SNAP depressions to be installed due to the fatigue that a driver experiences during extended driving on such roads.
Various attempts have been made to provide a machine capable of quickly, accurately, consistently and precisely installing SNAP depressions. These attempts have been less efficient than desired. As such, it may be appreciated that there continues to be a need for a machine that can consistently form depressions in a continuous, non pausing, manner having precise placement and precise dimensions. The present invention substantially fulfills these needs.